Project Abstract: The overall objective of this project within the structure of Advancing Reliable Measurement in Alzheimer's Disease and cognitive Aging (ARMADA) is to provide a brief, comprehensive, readily available tool for early identification of age-related cognitive decline and dementia. This objective targets the goals of the NIA and the National Plan to Address Alzheimer's Disease, namely, to prevent and effectively treat Alzheimer's Disease (AD) by 2025. The proposed study also capitalizes on the prior investment by 16 NIH centers and institutes to support the creation of the NIH Toolbox for Assessment of Neurological Behavior and Function (NIHTB) and its standardization. To achieve our objective, the studies undertaken in this project will serve to validate the NIHTB and its enhancement with new state-of-the-art tests (NIHTB+) in diverse samples of cognitively healthy and impaired individuals over age 65. The NIHTB has been standardized on a general population sample from 3 to 85 years of age but not in clinically diagnosed samples of individuals age 65-85 with cognitive impairment and dementia, nor in cognitively healthy individuals over age 85. Validation will be carried out by nine sites across the US affiliated with NIA-funded Alzheimer Disease Centers (ADCs), making use of existing cohorts of diverse individuals, well-characterized by cognitive status, who have available in vivo biomarkers associated with AD, to recruit participants for ARMADA. SPECIFIC AIM 1: To validate the NIHTB and added tests (Aim 2, below, NIHTB+) in the trajectory from normal cognitive aging to dementia of the Alzheimer type (DAT). Study groups are race/ethnicity population based samples of: 1) older normal controls aged 65-85 (NCO); 2) amnestic mild cognitive impairment (aMCI, single or multi-domain); 3) early stage DAT; and, 4) cognitively normal individuals 86+ years of age, oldest old (NCOO) to extend the NIHTB+ beyond age 85. A fifth group of African American NCO and aMCI will be recruited to validate the NIHTB+ specifically in this under-represented group that may be at increased risk of DAT. SPECIFIC AIM 2: To expand the NIHTB by adding innovative instruments to assess neurological functions associated with cognitive aging, in collaboration with the Technology Core. SPECIFIC AIM 3: To validate the Spanish version of the NIHTB+ in a Hispanic sample of NCO, aMCI, and early stage AD.